The complexities of golf club design are known. The specifications for each component of the club (i.e., the club head, shaft, grip, and subcomponents thereof) directly impact the performance of the club. Thus, by varying design specifications, a golf club can be tailored to have specific performance characteristics.
The design of club heads has long been studied. Among the more prominent considerations in club head design are loft, lie, face angle, horizontal face bulge, vertical face roll, center of gravity, rotational moment of inertia, material selection, overall head size, and overall head weight. While this basic set of criteria is generally the focus of golf club designers, other design aspects unrelated to performance such as sound of the club head upon impact with a ball must also be considered.
As the size of golf club heads has increased, weight distribution has become a major design consideration. In particular, in the quest to design in additional discretionary mass, it has become desirable to decrease the wall thicknesses of the portions of the club head wall that do not improve mass properties. Additionally, composite materials have also been used in the past to replace various sections of the club head walls to further improve weight distribution and generate discretionary mass. Because of the thin walls, composite materials, and the large volumes of the golf club head; large portions of the heads act as membranes and vibrate relative to each other. In some instances, the vibration that takes place could result in an unappealing sound during impact between the golf club and the golf ball.
Golfers have become accustomed to hearing a particular sound when the golf club impacts the golf ball, especially when a large volume golf club is used. This “ideal sound”, although often a result of personal preference, can drastically turn into an unappealing sound if it varies too much from the above mentioned “ideal sound.”
Various sound tuning features have been incorporated into hollow bodied golf clubs to try and capture and maintain this “ideal sound”. One example is described in U.S. Pat. No. 6,852,038 to Yabu for a Golf Club Head and Method of Making the Same. In that example, a hollow body golf club head includes rib-like walls that form the inner surface of the sole and crown. The sound emitted into the hollow cavity due to contact with a golf ball is directed rearward and parted laterally by the ribs. Sound bars are included in some embodiments that are located a small distance behind the club face and extends between the crown and sole. The sound bars are included to further part the sound vibrations.
Another example is described in U.S. Pat. No. 5,718,641 to Lin for a Golf Club head that Makes a Sound when Striking the Ball. In that example, the golf club head includes a sound plate that is suspended in the hollow body of the club head that makes a sound and echoes the sound during impact between the club head and a golf ball. One edge of the sound plate is fixed to a wall of the hollow club head and the remaining edges are unattached so that the sound plate is able to vibrate to the remainder of the club head.
As an alternative to adding sound ribs or ridges, others have added features to golf club heads to improve rigidity of the club head by reducing relative vibration between opposing walls to reduce the energy that is waste din deforming the club head and to redirect that energy into the golf ball. For example, U.S. Pat. No. 6,524,197 to Boone for a Golf Club Head Having a Device for Resisting Expansion Between Opposing Walls During Ball Impact describes a feature designed for the above stated purpose. The golf club head includes a tensioning device that extends between the crown and sole. In particular, the tensioning device includes an elongated cylindrical member that extends through apertures in each of the crown and sole and enlarged ends that are unable to pass through the apertures. One of the enlarged heads is threaded so that a threaded end member may be used to tension the elongate cylindrical member thereby placing the hollow body in compression and increasing the rigidity of the hollow body.
It can be seen from above that despite numerous attempts to control the sound, the current art utilize heavy and burdensome objects such as ribs, ridges, panels, or even posts within the internal cavity of the golf club head to create structural stiffness, control vibration damping, and adjust the sound. The additions of these heavy and burdensome objects are undesirable not only because they are expensive to manufacture, but they could also add additional weight to the golf club head at locations that may not be desirable for performance optimization.
Hence, it can be seen that there is a need in the field for a golf club head that is capable of controlling the sound characteristics without heavy and burdensome objects inserted into the internal cavity of the golf club head. More specifically, there is a need for a golf club head that utilizes the pre-existing performance optimization components such as a composite member, and modifying the internal composition of the composite member to provide structural stiffness, vibration damping, and sound tuning characteristics.